1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves an undersea hydraulic coupling having improved guidance of the coupling members prior to sealing between the male member and the female member of the coupling.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with seals to seal the junction between the male and female members.
The female member generally has a cylindrical body with a relatively large diameter bore at one end and a relatively small diameter bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains the seals and receives the male portion of the coupling. The male member includes a cylindrical portion at one end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, the seals either abut the end, or face, of the male member or engage the male member about its circumference. The hydraulic fluid is then free to flow through the female and male portions of the coupling, and seals prevent that flow from escaping about the joints in the coupling.
A check valve may be installed in the female member and also in the male member. Each check valve is open when the coupling is made up; however, each check valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith III, an undersea hydraulic coupling with a radial metal seal is disclosed. This coupling provides a reusable radial metal seal which engages the circumference of the probe when it is positioned within the female member body. The metal seal is held in place by a cylindrical body or retainer. The retainer prevents escape of the metal seal from the female member body. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member. This coupling uses a pressure actuated metal c-ring seal. Among the advantages of this design are that it requires no pre-load mechanism, is tolerant to movement of the two halves of the coupling relative to one another, and allows greater tolerances between the couplings and the manifold plates. The retainer also may be used to pre-load the metal c-ring seal by urging it radially inwardly to engage the circumference of the male member. This is accomplished by positioning the seal on a shoulder within the female member bore, then locking the retainer against the seal.
In U.S. Pat. Nos. 4,832,080, 5,099,882 and 5,277,225 to Robert E. Smith III, undersea hydraulic couplings are shown having at least two radial metal seals for sealing between the male member and the female member receiving chamber. Pressure energized seals are shown which are configured to seal radially between the male and female members, and the couplings are pressure balanced for fluid communication through mating radial passages and the annular space between the members.
In U.S. Pat. Nos. 5,029,613 and 5,284,183 to Robert E. Smith III, undersea hydraulic couplings are shown having a sealing member with a metal lip projecting radially inwardly to form a radial metal to metal seal with the male member in response to fluid pressure in the coupling, and locking or retaining means for holding the seal against an internal shoulder in the female member. In the couplings of U.S. Pat. Nos. 5,029,613 and 5,284,183, the male member is preferably aligned and guided into the receiving chamber of the female member prior to sealing engagement of the radial metal seals with the male member or probe.
Improved guidance of the probe into the female member will help ensure higher seal reliability and longer seal life in undersea hydraulic couplings. Additionally, in couplings of the foregoing type, a vacuum sometimes occur during withdrawal of the male member from the receiving chamber or bore, because of high subsea pressures.